Couplings are utilized in systems, for example, vehicle steering systems to connect one shaft to another shaft. Vehicle steering systems typically include a driver interface, such as a steering wheel which is connected to one end of a steering column. When the driver rotates the steering wheel, the angular motion is transferred to the steering column which then rotates. Another end of the steering column is connected to the steered wheels of the vehicle through, for example, a rack and pinion gear. As the steering column rotates, the rack and pinion gear effects turning of the wheels to steer the vehicle in a desired direction.
Many steering systems include a steering assist mechanism which reduces an amount of force a driver must apply to rotate the steering wheel a desired amount. A typical mechanism includes a worm shaft which is coupled to a motor shaft of, for example, an electric motor, which drives the assist mechanism. The coupling must not only transfer torque from the motor shaft to the worm shaft, but also allow for stroke of the worm shaft along a central axis of the worm shaft.